华东师范大学Shi-Gang Sun研究小组取得一项新突破。他们研究了替换元素在增强富锂层状阴极的结构稳定性中的作用。相关论文发表在2023年4月7日出版的《美国化学会杂志》上。

在该研究中，研究人员以Li1.2Ni0.2Mn0.6O2为原型，揭示了“无序程度”(Li/ Ni混合)和界面结构稳定性(如TM-O环境、板/点阵，和Li+可逆性)之间的强烈的相关性。具体来说，由Mg/Ti替换引起无序的程度向相反的方向延伸，导致TM-O稳定性、Li+ 扩散和阴离子氧化还原可逆性的巨大差别，产生相当不同的电化学性能。通过建立在范式基础上的系统表征和分析，“无序程度”已被证明是一个强大的元素替换/掺杂材料改性的指标。

据了解，元素掺杂/替换已经被认为是一个提高分层阴极的结构稳定性的有效策略。然而，许多替代研究不仅缺乏对材料晶格中替换位点的明确识别，也难以有说服力地通过过渡金属(TM)-O共价理论加以严格解释，导致掺杂/替代方案的设计在黑暗中摸索。

附：英文原文

Title: Role of Substitution Elements in Enhancing the Structural Stability of Li-Rich Layered Cathodes

Author: Baodan Zhang, Yiming Zhang, Xiaotong Wang, Hui Liu, Yawen Yan, Shiyuan Zhou, Yonglin Tang, Guifan Zeng, Xiaohong Wu, Hong-Gang Liao, Yongfu Qiu, Huan Huang, Lirong Zheng, Juping Xu, Wen Yin, Zhongyuan Huang, Yinguo Xiao, Qingshui Xie, Dong-Liang Peng, Chao Li, Yu Qiao, Shi-Gang Sun

Issue&Volume: April 7, 2023

Abstract: Element doping/substitution has been recognized as an effective strategy to enhance the structural stability of layered cathodes. However, abundant substitution studies not only lack a clear identification of the substitution sites in the material lattice, but the rigid interpretation of the transition metal (TM)–O covalent theory is also not sufficiently convincing, resulting in the doping/substitution proposals being dragged into design blindness. In this work, taking Li1.2Ni0.2Mn0.6O2 as a prototype, the intense correlation between the “disordered degree” (Li/Ni mixing) and interface-structure stability (e.g., TM–O environment, slab/lattice, and Li+ reversibility) is revealed. Specifically, the degree of disorder induced by the Mg/Ti substitution extends in the opposite direction, conducive to sharp differences in the stability of TM–O, Li+ diffusion, and anion redox reversibility, delivering fairly distinct electrochemical performance. Based on the established paradigm of systematic characterization/analysis, the “degree of disorder” has been shown to be a powerful indicator of material modification by element substitution/doping.

DOI: 10.1021/jacs.3c01999

Source: https://pubs.acs.org/doi/10.1021/jacs.3c01999

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